Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 202214
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
314 PM MST Sun Aug 20 2017

.SYNOPSIS...Expect isolated to scattered thunderstorms during much
of the upcoming week. The greatest coverage of thunderstorms should
occur east to south of Tucson, but the lower deserts will not be
completely left out. Daytime temperatures will be close to seasonal
averages.

&&

.DISCUSSION...Synoptically, we have a nice low near the southern
California coast with high pressure to our east. A general
southerly flow between these features has brought deeper moisture
back into the picture over the past 36 hours. We have enough
moisture for thunderstorms with precipitable water values ranging
from 1.2 to 1.5 inches across the area. We`re just not getting
enough lift to tap into the conditional instability in any
meaningful way. The debris cloud from last night`s convection
breaks up just long enough to build additional cu fields before
putting a break on the solar insolation. We`ll keep a few showers
overnight, but nothing organized as a weak mid level impulse lifts
north of the area.

By tomorrow, the low near southern California will nudge a little
further east, wrapping in a little bit of drying from the
southwest. Isolated coverage should be the most we can manage
Monday into Tuesday, with storms tending to cling to the
mountains.

Upward trend for thunderstorms Wednesday and Thursday as an
impulse wrapping around the high center lifts from Mexico into our
area.

A pattern change by next weekend with strong high pressure over
western states. If that shifts to a position northwest of our area
that will give us another break.

&&

.AVIATION...Valid thru 22/00Z.
Scattered -TSRA/-SHRA east to south of KTUS through the valid
period, and isolated -TSRA/-SHRA possible west of KTUS this
afternoon into tonight. Otherwise, VFR conditions with cloud decks
8k-12k ft AGL. Surface wind variable in direction mainly less
than 12 kts, although brief gusts to near 30 kts vicinity TSRA.
Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Expect isolated to scattered thunderstorms favoring
locales east to south of Tucson this week. Normal diurnal wind
trends will occur aside from any gusty and erratic thunderstorm
outflows. Daytime temperatures will remain close to seasonal
normals.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...None.

&&

$$

Meyer/Rasmussen

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